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TAM A320 crash at Congonhas, Brazil

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TAM A320 crash at Congonhas, Brazil

Old 27th Jul 2007, 14:58
  #581 (permalink)  
 
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Well said BOAC - useful technical gen, here's what the pilots do...
A summary of what happens on a normal A320 landing, assuming a servicable aircraft...

Autothrust (A/THR) engaged and active
Ground Spoilers ARMED
MED (medium) Autobrake selected.

The thrust levers (T/L) are in the CL detent, the A/THR can set N1 anywhere between IDLE and MAX CLIMB. Typical N1 about 54% for a stable approach. During the flare, PF retards both T/L to IDLE. No finesse required, just move them back to the mechanical stop. When both T/L are at IDLE the A/THR disconnects.
The Ground Spoilers extend automatically (see above posts for logic). This extension activates the Autobrake - two seconds after extension brake pressure is applied to decelerate the a/c at 3 m/sec/sec (MED).
On touchdown PF selects reverse - IDLE or MAX as required. Note that with autobrake functioning correctly reverse selection will not affect the deceleration rate or stopping distance. Reverse Idle is selected at 70 kts and FWD idle at normal taxi speed. Autobrake is normally disconnected by PF pressing the brake pedals at the appropriate point.

PNF monitors
1. Ground Spoiler extension on lower ECAM
2. REV Amber then Green indication on N1 gauge
3. A/c deceleration - by feel, IAS trend arrow, and Green DECEL light in Autobrake pushbutton (light indicates 80% of selected decel rate achieved).
PNF calls "Ground Spoilers, Reverse Green, Decel" as they are observed - (or calls a malfunction) .. then "70 kts".
TP
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Old 27th Jul 2007, 15:04
  #582 (permalink)  
 
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@TyroPicard

Yes, that's normal ops.

Was Conghonas normal ops?

Last edited by hetfield; 27th Jul 2007 at 16:10.
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Old 27th Jul 2007, 15:27
  #583 (permalink)  
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TwoOnefour;

The speed data derived from the FDR was officially released a few days ago -
Ok, thanks, I hadn't seen the info nor the notice here that the information was from the DFDR and that wasn't intimated in the post.

c9jfb

The mode you speak of is known very well by all AB pilots and is called "A-Floor" or Alpha-floor protection. The autoflight computers sense angle-of-attack and if too great, will place the autothrust in the TOGA (full thrust) mode and protect the pitch attitude to keep the angle-of-attack below the stall angle. Speed is respected and controlled by the flight computers through the elevators, so as long as the aircraft has sufficient energy the crew can fly the aircraft with full sidestick back-pressure (to the stop) and even do 20-degree bank turns in this mode. Obviously, physics still applies and the aircraft will still descend if in heavy windshear downdraft but the aircraft will be at it's maximum climb performance even in gusts. Disengaging A-Floor autothrust protection is done by disconnecting the autothrust either through the instinctive disconnect buttons on the sides of either thrust lever or the autothrust "ARM" button on the FCU (flight control unit).

However, as TyroPicard has stated correctly, the scenario you describe cannot occur because Alpha-prot is disengaged below 100ft. This is why the Airbus accident at Habsheim was not an "Airbus" accident where the autoflight - autothrottle systems somehow failed, but a crew/human factors accident. The crew had dis-armed the A-floor protection by pulling a circuit-breaker which means they were never intending to fly below 100ft (as they knew the demonstration they were considering would have engaged alpha-prot and "ruined" the demonstration). Instead, the narrow, short grass strip proved an optical illusion and they flew at about 30ft instead of higher than 100ft (where Alpha-prot would have been active). This isn't the place or thread to go into why this is so however but there remains huge misconceptions and even conspiracy theories about this accident and the sophisticated autoflight systems of this design. Sorry for the thread diversion, but it helps explain the AB autoflight system a bit more.

I think PBL's posts are well worth reading with care and thought.

BOAC;

TRAINING.
Absolutely. Unlike the early 90's when instructors were 24hrs ahead of the students, there is sufficient experience and knowledge about this aircraft now to make it "old hat" so there is no excuse for not knowing these very basic facts about the Airbus product. The aircraft is exceptionally well conceived and executed but it requires about six months to a year of flying it before it becomes second-nature. In this sense, the attractiveness of the Boeing as a bread-and-butter transistion is that such a "break-in" period has never been necessary and the designs are a delight to fly. Pilots love familiarity and predictability and the Boeing delivers this in spades, (although the 78' is going to be an interesting introduction). That said, the Airbus design is now at that same level of familiarity within the industry but the airplane's autoflight systems are more complex and require the training that you so correctly emphasize. The entire difficulty has been, however, that managements were "sold" (and, with dollars in mind, they bought) the notion that "automation" would "solve" their training issues and so gradually the pilot-training footprint was reduced with the result that comprehension of the autoflight/autothrust system was marginal in a few cases. The training savings came for common cockpits in different types however, and not on the initial transition course. Transition courses are all the same - they take about 56 days to complete for new, non-AB candidates but crew "downtime" these days is under tremendous pressure so footprints are reduced.

None of this relates to or comments upon, the crew in the accident aircraft who by all accounts were highly experienced professionals.

I apologize for the thread-drift once again and justify it only in the sense that it may provide a bit further understanding. I am glad you're beginning another thread on this as the topic is in need of discussion especially in today's extremely cost-concious (penny-wise, pound-foolish, is the way I'd put it), environment.
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Old 27th Jul 2007, 15:37
  #584 (permalink)  
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Hello Tyro - following Hetfield's post, the scenario I am looking at is when only one T/L is put at idle, and then it seems the whole can of worms opens - only partial spoilers, no autobrake, and then to really make your day, the 'dead reverser' engine goes back to 54%'ish - and you are on a short and slippery runway. Apart from getting pilots to actually close the throttles at landing, what can be done?

PJ2 - please join!

http://www.pprune.org/forums/showthread.php?p=3441160
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Old 27th Jul 2007, 18:14
  #585 (permalink)  
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The B is the X of the question

The last Airbus’ Accident Information Telex (AIT)
A- During the flare at thrust reduction select ALL thrust levers to IDLE.

B- For the use of the thrust reversers when landing with one Engine Reverser inhibited refer to:

- For A320 MMEL 02-78-30 Rev 30
Does anyone know CLEARLY and EXACTLY what are the B recommendations? All pilots have not the same interpretation of the document.

Thank you very much.

Last edited by A22; 27th Jul 2007 at 19:39.
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Old 27th Jul 2007, 19:21
  #586 (permalink)  
 
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I think that Airbus did not have any kind of official information about the accident prior to issuing that statement. In other words, they could not issue a serious statement without the conclusion of the investigation...About the TL above idle at flare: I can’t really see that happening! Would make more sense to me a "Thrust lever fault" at low altitude (the warning might have been inhibited due to landing proximity).
At TAM, some aircrafts are equipped with a LIP (lift improvement package), witch changes the airplane handling at landing. It is common to keep the engines at CLB detent until 20 or 15 feet on this kind of aircraft (similar to a 737 Efis flare), or you might have a very hard landing.
But MBK did not have the LIP, so...
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Old 27th Jul 2007, 19:43
  #587 (permalink)  
 
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I think that Airbus did not have any kind of official information about the accident prior to issuing that statement.
Rippa

I disagree dear fellow. Airbus said that its statement was based on "preliminary analysis" of the DFDR.

With any number of factors potentially contributing to a landing accident, Airbus wouldn't have issued such a specific reminder about such a particular action without a reason.

It may only be a piece of the puzzle but the smart money is certainly on a failure to retard the throttle to idle. Why else would Airbus make such a notable remark about something which is ultimately a basic aspect of landing an aircraft?
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Old 27th Jul 2007, 20:13
  #588 (permalink)  
 
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...
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Old 27th Jul 2007, 20:44
  #589 (permalink)  
 
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Thrust Lever Fault: FCOM 03.02.70
According to the FCOM, warning will be inhibited at flight phase 5 only (liftoff until 1500ft).


No validated thrust lever angle for one engine thrust lever.
On the ground :
ENG (affected) IDLE POWER ONLY.
FADEC selects idle power automatically.
If associated thrust reverser is already deployed, FADEC commands restow.


In flight :
If the selected thrust lever position at the time of fault detection is :
TO or FLEX
: FADEC freezes TO or flex TO thrust until slat retraction. At slat retraction it will select MCT thrust.
Between IDLE and MCT
: in manual thrust setting mode, engine rating increases and freezes at max continuous. It is possible to activate autothrust. If selected, autothrust mode will manage thrust between idle and MCT.

A/THR engaged :
-A/THR KEEP ON
A/THR not engaged :
ENG (affected) HI PWR IN MAN THR.
BEFORE SLATS IN :
-A/THR ON
STATUS


APPR PROC
THR LEVER
-AUTOLAND USE
IF AUTOLAND NOT USED :
AT 500 FT AGL :
-ENG MASTER (affected) OFF
Affected engine must be shut down, because when thrust levers are retarded, autothrust would remain in SPEED mode. During flare the thrust of the affected engine would increase to maintain the autothrust target speed
.
If autoland scheduled :
Thrust is reduced automatically during flare.
ON GND ENG 1(2) MAX PWR : IDLE.
INOP SYS
REVERSER 1(2)
ENG 1(2) THR
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Old 27th Jul 2007, 21:11
  #590 (permalink)  
 
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Even after touchdown ?
Not sure on this point, but I believe so.
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Old 27th Jul 2007, 21:23
  #591 (permalink)  
 
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Hi BOAC
the 'dead reverser' engine goes back to 54%'ish
Not necessarily .. normally when A/THR is disconnected the N1 goes to the value determined by the T/L position.. if the kit disconnects it due to a malfunction the thrust is locked at current value, ECAM warning displayed, and you then sort it out by moving the T/L to give the desired thrust. In the Transasia overrun T/L 2 was left at 22.5 deg (CL is 25.0 deg) and thrust was 1.08 EPR which sounds like an approach value to me.. but I don't know if it was locked at that value.

What I cannot find in my FCOM is any mention of automatic A/THR disconnect on landing if the T/L is not retarded correctly - can anyone explain/point me at a reference?

On to
Partial spoilers
this will only happen if one T/L is in reverse and the other is at or near idle (below 15deg).. if you leave one T/L above 15deg the a/c does not think you wish to stop - quite logical really. Partial spoiler extension is actually aimed at the "one-leg landing" to ease the a/c onto the tarmac, when the second gear strut is compressed you get full ground spoiler and autobrake.

hetfield
I consider one reverser inop to be normal ops. It ain't covered by an abnormal or emergency drill, so it must be normal. Your point is?
Cheers
TP
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Old 27th Jul 2007, 22:16
  #592 (permalink)  
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flyingnewbie10, Rippa;

Re, "even after touchdown", yes, that is the case - depending upon when the thrust lever fault occurred, unless an autoland is performed, the engine thrust level will remain at the level it was when the fault occurred*.

In a "thrust lever fault" the engine must be shutdown for landing if an autoland (autothrust engaged) is not planned. The sim exercise was an interesting one...the fault occurred in a LOFT session out of LAX, and over Reno, which was perfectly clear and 35C, directly below us, while SFO was 200 & a half well behind us. But the approach in Reno was a localizer from the south to the north, huge programming demands, and with no autoland capability (no ILS) the engine would have to be shut down. After examining the missed approach climb gradient requirements, we turned around for SFO and did the autoland, avoiding shutting down the engine and a whole lot of dumb time-consuming programming of waypoints with speeds and altitudes, (the LOC wasn't in the database).

I provide the fault experience in the sim once again only to illustrate the thinking which goes on in an AB where abnormalities with the autothrust is concerned.

TyroPicard, this is what I could find in our AOM, at 1.03.71 P3, Supplementary Techniques - Power Plant:

Use of autothrust in approach
The pilot should use autothrust for approaches. On final approach, it usually gives more accurate
speed control, although in turbulent conditions the actual airspeed may vary from the target speed, by
as much as five knots. Although the changeover between auto and manual thrust is easy to make with
a little practice, the pilot should, when using autothrust for the final approach, keep it engaged until he
retards the thrust levers to idle for touchdown. If the pilot is going to make the landing using manual
thrust, he should disconnect the A/THR by the time he has reached 1000 feet on the final approach.
If he makes a shallow flare, with A/THR engaged, it will increase thrust to maintain the approach speed
until he pulls the thrust levers back to idle. Therefore he should avoid making a shallow flare, or should
retard the thrust levers as soon as it is no longer necessary to carry thrust, and if necessary before he
receives the “retard” reminder

*From the AOM Abnormals Chapter, Eng 1(2) Thr Lever Fault

In flight :
If selected thrust lever position at the time of fault detection is :
TO or FLEX : FADEC freezes TO or flex TO thrust until slat retraction. At slat retraction it will select
CLB thrust.
Between IDLE and MCT : in manual thrust setting mode, engine rating increases and freezes at CLB
or IDLE with slats extended (or MN < 0.47 if the FADEC no longer receives the slats position due to
EIU failure). It is possible to activate autothrust. If selected, autothrust mode will manage thrust
between idle and CLB.
– ENG (affected) AT IDLE
For any case of thrust lever fault (TO, FLEX or between IDLE and MCT) the FADEC will command
idle thrust for the approach when slats are extended (or when MN < 0.47 if associated EIU is
failed). It is independant of the autothrust condition. Thrust of affected engine remains definitively
at idle even for go around.
– THR LEVER (affected) ............................................................ .................................................IDLE
When slats are extended or MN < 0.47, if on side EIU is failed.
A/THR engaged :
– A/THR......................................................... ............................................................ ......KEEP ON
A/THR not engaged :
ENG (affected) HI PWR IN MAN THR.
Inhibited when the FADEC commands the affected engine at IDLE.
BEFORE SLATS IN :
– A/THR......................................................... ............................................................ ...........ON
HI POWER ONLY (if thrust lever angle failed in TO or flex position).
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Old 27th Jul 2007, 22:22
  #593 (permalink)  
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Have they fixed?

Have they fixed it ?
Airbus stated that every time a recommendation is made from an Occurrence Investigation Report, such as the one of Aviation Safety Council of Taiwan, the company follows it. If it was the case, there still another question. Was it installed on TAM A320?
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Old 28th Jul 2007, 05:18
  #594 (permalink)  
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IMO there is nothing to fix, if you have to remind a pilot to retard thrust levers during landing, they have NO business being crew members on a flight deck.
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Old 28th Jul 2007, 09:57
  #595 (permalink)  
 
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Runway 35L/17R at Congonhas has now apparently reopened but with "restrictions" for wet weather landings.
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Old 28th Jul 2007, 10:58
  #596 (permalink)  
 
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Brazil air crash runway re-opened

Congonhas airport is very close to Sao Paulo city centre

The main runway at Sao Paulo's Congonhas airport has been re-opened 10 days after a passenger plane overshot it in Brazil's worst aviation disaster.

But landings will be restricted in wet weather until the surface is grooved to improve the drainage of rainwater.

Nearly 200 people died when a TAM Airlines Airbus 320 landed in wet conditions, crashed into a nearby building and burst into flames.

There has been intense speculation but no confirmation of the crash's cause.

The accident has led to air travel chaos in Brazil, where there have been mass cancellations and delays.

Investigation

The main runway at Congonhas was re-opened on Friday after being inspected by Brazil's new Defence Minister, Nelson Jobim.

Mr Jobim, whose ministry oversees air traffic control, was appointed on Wednesday. His predecessor was sacked after being criticised for being inefficient.




Q&A: Plane crash

A TAM plane was the first to touch down on the 1,939m (6,362ft) runway, which was resurfaced only weeks before the accident.

Planes will continue to land on the 1,436m (4,711ft) secondary runway in wet conditions until the main surface has been completely grooved - a process that could take weeks.

Investigators are still trying to determine if the main runway's condition and length played a role in the accident.

Tam Airlines has said that one of the two thrust reversers on the Airbus 320 - which help jets slow down on landing - had been deactivated on the plane during maintenance checks.

But the company insisted that the deactivation was in accordance with proper procedures.

Video footage appeared to show the plane travelling along one section of the runway at higher than normal speed, taking only three seconds to cover the same distance the previous plane had done in 11.
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Old 28th Jul 2007, 11:18
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The main runway at Congonhas was re-opened on Friday after being inspected by Brazil's new Defence Minister, Nelson Jobim.
Now THAT's reassuring

As always there are will be many contributing factors to this crash but from early Airbus communication it seems pretty evident that the crew managed to put themselves in an inextricable situation
Now was it negligence, distraction, ignorance or gross incompetence is another story...

This runaway is perfectly safe to operate but unforgiving to mistakes. It will take some major engineering work to change that, if at all possible...
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Old 28th Jul 2007, 11:23
  #598 (permalink)  
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This runaway is perfectly safe to operate but unforgiving to mistakes
Thanks for the expert advice, I personally think I will wait for the grooving.
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Old 28th Jul 2007, 11:33
  #599 (permalink)  
 
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Well I guess everyone would love to have it grooved, 3000ft added and an EMAS built... but safety is always about compromises. Let's rephrase my post to say "reasonably safe".
I would be happy to land an A320 there anytime except during major thunderstorms or other exceptional events.

Last edited by atakacs; 28th Jul 2007 at 20:03.
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Old 28th Jul 2007, 12:08
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From TyroPicard's post above:

PNF monitors
1. Ground Spoiler extension on lower ECAM
2. REV Amber then Green indication on N1 gauge
3. A/c deceleration - by feel, IAS trend arrow, and Green DECEL light in Autobrake pushbutton (light indicates 80% of selected decel rate achieved).
PNF calls "Ground Spoilers, Reverse Green, Decel" as they are observed - (or calls a malfunction) .. then "70 kts".

See number 3. The clues are there if people use them.
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